Encapsulated inductor with external adjustable means for selectively varying the inductance



Sept. 3, 1968 G. w. HENKE 3,400,352 ENCAPSULATED IND UCTOR WITH EXTERNALADJUSTABLE MEANS FOR SELECTIVELY VARYING THE INDUCTANCE Original FiledJan. 2, 1962 J /a /3 l4 F IG 2 FIG FIG 3 FIG. 4

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United States Patent ENCAPSULATED INDUCTOR WITH EXTERNAL ADJUSTABLEMEANS FOR SELECTIVELY VARY- ING THE INDUCTANCE Gustave W. Henke,Freeport, N.Y., assignor, by mesne assignments, to Varian Associates,Palo Alto, Calif., a corporation of California Original application Jan.2, 1962, Ser. No. 163,936, now Patent No. 3,239,782. Divided and thisapplication Mar. 7, 1966, Ser. No. 558,154

4 Claims. (Cl. 336-75) ABSTRACT OF THE DISCLOSURE There is disclosedencapsulated variable inductors provided with externally adjustablemeans in the form of a coaxial ring or nut adapted to be moved along thelength of the inductor for adjusting the inductance. The ring isprovided with a resilient inner portion which engages the encapsulatedinductor to maintain the adjusted inductance.

This is a division of application Ser. No. 163,936, filed Jan. 2, 1962,now Patent No, 3,239,782.

This invention relates to continuously variable inductors and morespecifically to those of miniature type which might also be encapsulatedto exclude the effects of moisture and other effects.

One of the objects of the invention is to provide exact adjustment ofinductance with minimum cost in construction and assembly.

A specific object of the invention is to improve over the prior methodsof varying an inductance; these prior methods consist mainly of theinsertion of a ferrous or non-ferrous metallic slug inside the windingsof an inductance.

Another object of the invention is to provide a solenoid inductor ofcylindrical external shape or any shape allowing for the placement of ascrew thread coaxially with the winding of the inductance. A metallicnut or sleeve screwed over these threads will cause the inductance todecrease as the position of the nut moves to the center of the coil.

These and other objects of the invention will be more fully apparentfrom the drawings enclosed herewith in which FIG. 1, shows a miniaturetype of variable inductor.

FIG. 2 represents a corresponding circuit diagram.

FIGS. 3 and 4 show a modification of this embodiment in a more simpleform not requiring the use of a screw thread.

FIG. 5 illustrates another modification of the invention involving athread on insulating material.

FIG. 6 represents variable inductor embodying the invention in the formof an auto-transformer.

FIG. 7 represents a corresponding circuit diagram.

FIG. 8 shows two inductors in accordance with the invention adjustablesimultaneously.

FIG. 9 shows a variable inductor adjustable by means of a special toolwhich is illustrated in a side view shown in FIG. 10.

FIG. 11 shows the invention as applied to a radio frequency transformer.

FIG. 12 shows an adjustable miniature inductance in accordance with theinvention permitting fixation of the adjustment.

FIG. 13 shows a modification of the embodiment shown in FIG. 12.

FIG. 14 shows a variable inductance in accordance with the invention inthe form of a double tuned circuit, and FIG. 15 shows the correspondingcircuit diagram.

3,400,352 Patented Sept. 3, 1968 In FIG. 1 a plastic or other insulatingcapsule 1 containing a coil not shown is provided at least at a portionthereof with a thread schematically indicated at 2 over which metal nutor ring 3 is adjustable to permit adjustment of the inductance inaccordance with the equivalent circuit diagram of coil 4, shown in FIG.2.

The actual size of such a miniature type variable ind-uctance can be ofthe order of less than an inch, its length for example being half aninch and its outer diameter /s of an inch, while the metal ring 3 has anouter diameter of A of an inch. The terminal leads are indicated at 5,6, respectively.

The modification of FIG. 3 shows in schematical form a coil capsule orcylinder 7 having axial end leads 8, 9 extending therefrom. Movablealong the outside of cylinder 7 is a shorted turn of wire schematicallyindicated at 10, permitting the inductance of the coil enclosed in 7 tobe changed in a continuous movement.

As apparent from FIG. 3 shorting wire 10 is also connected to axial lead8 by means of a wire 11 permitting to the adjustment of the inductor tobe held at a fixed value, if desired.

FIG. 4 shows a metallic ring 12 with diagonal clips 13, 14, and arrangedto be movable over the outer surface of capsule 15. In this way, threadson the capsule are not required.

According to FIG. 5, the inductor capsule 16 is provided with a sleeveof insulating material 17 which is arranged with push-fit over capsule16, and which has an outer thread permitting adjustment of metal nut 18over sleeve 17.

In the embodiment of FIG. 6, the inductor capsule 19 is provided withtwo axial end leads 20, 21 and a center tap lead 22 permitting it to actas an auto transformer with variable tap.

Adjustment of inductance is elfected by nuts 23, 24 adjustable overcorresponding threads, or thread portions of capsule 19.

The equipment circuit diagram is indicated in FIG. 7.

FIG. '8 shows two inductor capsules 25, 25 arranged in parallel andprovided with adjustment rings 27, 28 movable over outer threads undercontrol over a common gear element schematically indicated at 29 andmeshing with outer gears formed on nuts 27 and 28, respectively.

FIG. 9 shows the adjustment element or ring 30 movable over thread 31 ofan inductor capsule under control of grooves 32 peripherally provided onthe outside of nut 30. In the side elevation of FIG. 10, an adjustingtool 33 is indicated which has projections fitting into grooves 32 ornut 30 and permitting adjustment of inductance.

FIG. 11 illustrates the invention in the form of a radio frequencytransformer.

The coil in the capsule of FIG. 11 consists of two separate winding-s,primary and secondary, indicated at 35, 36, respectively withcorresponding terminal leads projecting at one end at 37, 38, 39, 40,respectively.

Adjustment nut 41 is movable over thread 42 to adjust or trim theinductance. If desired, windings 35, 36 may be provided instead ofinside capsule 34, outside thereof, and of proper diameter and pitch toform a thread for direct application of adjustment nuts.

FIG. 12 shows an adjustment nut consisting of an inner core ofinsulating material schematically indicated at 43 which is pressed intoa metallic outer ring or sleeve of metal schematically indicated at 44.The soft inner ring 43 is threaded over the thread provided oninductance capsule 45 to permit the soft material to hold adjustment.

In the arrangement of FIG. 13 metal nut or nuts schematically indicatedat 46 are used to adjust the inductance capsule 47.

A nut of flexible material 48 may be used to hold metal nut 46 inadjustment.

Nut 48, may also be of metal to act as a lock nut, but it should benoted that additional metal nut or nuts decrease the inductance value.

It should also be noted that all rings, sleeves or nuts which are usedfor adjustment with respect to the inductor capsule may be covered withinsulating material to prevent possible electrical contact and shortcircuit with other components or wiring.

FIG. 14 shows a variable inductor in the form of a double tuned circuitas illustrated in the equivalent circuit diagram of FIG. 15.

In this case, the inductor capsule schematically indicated at 49contains three windings or coils schematically indicated at 50, 51 and52 and extending into end leads or terminals 53, 54 and 55,respectively.

Capsule 49 is provided with an external screw thread 56 on which theyarranged three nuts adjustable in accordance with the invention andschematically indicated at 57, 58, 59.

The invention is not limited to the particular shape of the inductorcapsule nor to the arrangement and number of windings or coils shown anddescribed nor to the particular circuit configuration and adjustmentmeans which have been illustrated but may be applied in any form ormanner whatsoever without departing from the scope of this disclosure.

I claim:

1. An inductor comprising a substantially cylindrical encapsulatingmeans having opposite closed ends, at least one winding located in andextending axially of said encapsulating means, said winding havingterminal leads projecting through at least one of said closed ends ofsaid encapsulating means, and at least one ring means circumferentiallysurrounding said encapsulating means and said winding therein and beingaxially movable along said encapsulating means between said endsthereof, said ring means comprising metallic material for adjusting theinductance of the winding as the ring means translates axially of saidwinding, wherein said ring means is provided with gripping meansflexibly holding said ring means against said encapsulation.

2. The inductor of claim 1 wherein said ring means comprises an outermetal ring portion and an inner ring portion, said gripping meanscomprising said inner ring portion, said inner ring portion being ofresilient material engaging said capsule for holding adjustment.

3. The inductor of claim 2 wherein said inner ring consists ofinsulating material.

4. The inductor of claim 1 wherein said ring means comprises an outermetal ring portion and an inner ring portion, said gripping meanscomprising said inner ring portion, for holding adjustment.

References Cited UNITED STATES PATENTS 7/1956 Ashby et al. 336l36 XR5/1959 Fleming 336-96

